In the prior intelligent network, the system and method for realizing a coloring ring back tone are conducted as follows: when a caller starts a call, a calling or called exchange triggers an intelligent network service (the first intelligent network service), and the service directs the exchange to connect the call to an intelligent peripheral (IP), then the intelligent peripheral (IP) triggers a coloring ring back tone service (the second intelligent network service), the coloring ring back tone service directs the IP to connect the called, and plays a coloring ring back tone to the caller. Specifically, the coloring ring back tone service system is used to provide a coloring ring back tone service to the subscriber in mobile communication system. Said mobile communication network includes a caller, a called subscriber (or called), a home location register (HLR), a MSC, and a base station. Said coloring ring back tone service system includes a signal interface unit (SIU), a service control point (SCP), a service management unit (SMP), and a coloring ring back tone server, wherein the SIU, SCP, SMP are interconnected with Transmission Control Protocol/Internet Protocol (TCP/IP), and SIU is also connected to mobile communication network through a No. 7 signaling network, while the coloring ring back tone server stores coloring ring back tones and is connected to the mobile communication system through the signaling system No. 7 and speech channel trunk. When calling, the coloring ring back tone is transmitted to the caller by the coloring ring back tone server. Said coloring ring back tone server is a SPC (stored program control) switch as a physical device.
The method for realizing the coloring ring back tone service includes the following steps: step 1: the subscriber of the mobile communication network sets up a HLR-based unconditional call forwarding number by cell phone, wherein the forwarding destination number is the number of the coloring ring back tone service system; step 2: a caller calls a called, and the call from the caller is transmitted to a coloring ring back tone server; step 3: the coloring ring back tone server triggers the coloring ring back tone service, interacts with the SCP, and decides the service flow and the music or speech that needs to be played; step 4: the coloring ring back tone server plays a coloring ring back tone and continues the call connection.
However, in this networking method, when the first service directs to connect the call to an IP, since the trunk from the exchange to the IP is occupied, or the IP outgoing trunk is occupied, or the IP fails in triggering the service, etc. the phenomenon that the called subscriber can not receive the call will occur, which means the call completion ratio decreases due to the reason that the subscriber applies for a new service. Thus it will result in the dissatisfaction of subscribers with the telecommunication service.